Barium Aluminates

Freshly precipitated aluminium hydroxide is dissolved by barium hydroxide solution with the formation of barium aluminates. Metallic aluminium is also attacked by barium hydroxide solution. The following compounds have been described: Al2O3.BaO.6H2O, or 5H2O, Al2O3.2BaO.5H2O, and Al2O3.3BaO.11H2O. Lower hydrates may be obtained by heating. Halogen compounds are also known, Al2O3.BaO.3BaCl2.6H2O, Al2O3.BaO.BaCl2.11H2O, Al2O3.BaO.BaBr2.11H2O, and Al2O3.BaO.BaI2.11H2O.